The characteristics of ceramic coating technology Compared with the overall structure of ceramic materials, ceramic coating technology has the following characteristics:
1. It can organically combine the strength and toughness and easy processing of metal materials with the high temperature resistance, wear resistance and corrosion resistance of ceramic materials.
2. Reasonable selection of coating materials and appropriate spraying process can obtain various functional surface strengthening coatings.
3. Not restricted by the substrate: the substrate material used for thermal spraying can be inorganic materials such as metal, ceramics, cement, refractory materials, stone, gypsum, etc., or organic materials such as plastic, rubber, wood, paper, etc.
4. Not limited by the size of the workpiece and the construction site.
5. The coating deposition rate is fast, the thickness is controllable, and the process is simple. 6. The ceramic coating has good workability, and spraying can be carried out after the coating is damaged.
The application fields of thermal spray ceramic coating technology are very wide, mainly including:
1. Thermal barrier coating. The key components of aero-engines are superalloy turbine blades and turbine disks. These heated components are exposed to harsh environments such as high temperature, oxidation and high-speed air erosion. For gas turbine components that can withstand temperatures up to 1100°C, which has exceeded the temperature limit (1075°C) used by nickel-based superalloys, an effective solution is to apply a high-melting-point ceramic coating with good thermal insulation, called thermal barrier coating.
Thermal barrier coatings are mainly used for heating components of aviation, naval ships and land-use gas turbines, as well as civil internal combustion engines, turbocharged turbines, and oxygen lances for metallurgical industries.
2. High-temperature adhesive and wear-resistant coating: heat treatment furnace rolls, support rolls, sintering furnace rolls and other high-temperature rolls are mostly operated at a high temperature of 800 ℃-1200 ℃. Thermal spraying technology is used to spray special ceramic or cermet coating on the surface of the high-temperature furnace roll. The layer has good high temperature resistance, anti-oxidation, anti-adhesion, anti-nodule and self-cleaning and purification functions, which can significantly increase the life of the furnace roll and produce steel with good surface smoothness.
3. Wear-resistant and corrosion-resistant coating: chemical plant uses high-pressure reciprocating metering pump plunger, spraying Al2O3-TiO2 composite coating instead of the traditional chrome plating process, and its service life is increased by 6 times. Under low-stress sliding wear and abrasion conditions, almost all original chrome-plated products can be replaced with thermal spray ceramic coatings.
4. Functional coating: plasma sprayed supersonic sprayed superconducting ceramic coatings have been successfully applied. Superconducting ceramic coatings have shown good application prospects in magnetic shielding, microwave components, various types of transmitters, and quantum electronic devices. Spraying a 30μm BaTiO3 coating on a 0.1mm iron sheet, its dielectric constant exceeds 6000, and has been widely used in ceramic chip capacitors. When the thickness of the Al2O3 coating formed by plasma spraying is less than 1mm, it can withstand a voltage of over 2500°C at a high temperature of 1300°C, which meets the requirements for high-temperature electrical insulation. Spraying bioactive ceramics such as 50-75μm hydroxyapatite on the titanium alloy substrate provides good chemical compatibility. Therefore, it can be used as an ideal artificial bone material.
There are a lot of corrosion and wear problems in oilfield drilling and oil production engineering. It can be expected that thermal spraying technology and ceramic coating have a wide range of application prospects.
